1. Field of the Invention
The present invention relates to a choke tube attached to a muzzle of a barrel of a shotgun.
2. Description of the Related Art
A screw-in choke tube of a shotgun includes a tube body composed of carbon steel or stainless steel. A hard coating, such as a TiN film (titanium nitride film), a CrN film (chromium nitride film), a TiAlN film (titanium aluminum nitride) and a TiCN film (titanium carbide nitride film), is applied over the inner surface (the barrel) of the tube body in some proposed devises. This coating is effective to improve the wear resistance on the inner surface. Such coating for gun is, for example, disclosed in JP-A 08-313195, its title being “hunting rifle having hard film on internal surface of muzzle of its barrel”.
The choke tube has a different ballistic pattern depending on the inner shape thereof. Therefore, a plurality of choke tubes having a variety of inner shapes are prepared to achieve different design ballistic patterns such that the user can select a desired design ballistic pattern.
Even if the choke tubes have different design ballistic patterns, however, they are designed to exhibit the same appearance as commodities in general. In this case, the design ballistic patterns are identified by character information, such as trade names and model numbers, described on outer surfaces. Accordingly, it is difficult for the user to simply identify the design ballistic patterns that are respectively set for the choke tubes.
This may lead to the following consideration. Namely, different colors are prepared for respective inner shapes of the choke tubes having different design ballistic patterns. The colors corresponding to the design ballistic patterns associated with the inner shapes of the choke tubes may be printed on the outer surfaces of the tube bodies. In such the case, application of colors in a post-process elevates work costs. In addition, a printing process, capable of achieving stable fixture against heat during shooting, causes an increased price as a problem.
The inventor has paid attention to colors of wear resistant coatings applied to the choke tubes, which differ depending on materials of the wear resistant coatings. In consideration of the above situation, the present invention has a subject matter to color-code outer surfaces of choke tubes based on design ballistic patterns set for the choke tubes, not depending on coloring in a post-process. In addition, the present invention has an object to identify the design ballistic patterns simply by the colors applied to the choke tubes.